Parental improvement in the SRA sugarcane breeding program

PARENTAL IMPROVEMENT IS an integral and key component of commercial genetic improvement programs. Unfortunately, its importance has not been fully realised and has often been ignored in sugarcane breeding programs around the world, partly due to its difficulties, long-term efforts and clonal deployment. In the SRA breeding program, as in many other breeding programs, the improvement of parents has been hampered by the lack of understanding of genetic control of sugarcane traits and inadequate or mixed information that could be used to assess the quality of sugarcane clones as parents. A parental clone may have a predicted breeding value (PBV) based on the performance of its progeny in progeny assessment trials or predicted genetic value (PGV) based on its own performance. Because of underlying genetic control differences, it becomes difficult to compare PBVs estimated from progeny performance with PGVs estimated from own performance. In this study the relationship between different parental information and their progeny performance was investigated, and genetic control of cane yield (TCH) and sugar content (CCS) was studied. Results indicated that PBV was more associated with progeny performance than PGV, and the different sources of parental information (PBV, PGVs) should not be mixed to evaluate parents. Cane yield and CCS were under stronger non-additive genetic control than previously estimated. Narrow-sense heritability was estimated to be from 0.11 to 0.13 for TCH and from 0.19 to 0.25 for CCS. Genetic gains from one generation of improvement could be expected to be 10.2 tonnes for TCH and 1.1% for CCS.